Refrigeration apparatus which injects an intermediate-gas liquid refrigerant from multi-stage expansion cycle into the compressor
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Solution Overview
Problem
In refrigeration apparatuses, the inclusion of a liquid-gas heat exchanger reduces the effect of injecting intermediate-pressure gas refrigerant into the compressor, leading to a decrease in the coefficient of performance (COP) and inadequate energy efficient heating operation, especially in cold climates where outdoor air temperatures are low.
Innovation Solution
A refrigeration apparatus with a gas injection pipe that directs intermediate-pressure gas refrigerant from a gas-liquid separator into the compressor, combined with a liquid-gas heat exchanger that exchanges heat between evaporating and condensing refrigerant, and an intermediate pressure setter to optimize the liquid-to-gas temperature difference, ensuring a sufficient degree of superheat and gas refrigerant injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a liquid-gas heat exchanger is included to increase the degree of superheat of refrigerant, then the temperature of discharged refrigerant increases and space heating capacity increases, but the effect of injecting intermediate-pressure gas refrigerant into the compressor is reduced and the coefficient of performance decreases
Solution Approach 1:
The patent optimizes the temperature difference parameter between liquid and gas refrigerant in the heat exchanger to achieve the required degree of superheat while minimizing energy loss. By carefully controlling this temperature difference parameter, the system balances the competing requirements of achieving sufficient superheat for heating capacity while maintaining efficient compressor operation through intermediate-pressure gas injection.
2Productivity
If intermediate-pressure gas refrigerant is injected into the compressor to increase the amount of refrigerant circulating through the utilization-side heat exchanger, then the space heating capacity increases and the coefficient of performance increases, but the effect is reduced when a liquid-gas heat exchanger is merely included
Solution Approach 1:
The patent optimizes the temperature difference parameter between liquid and gas refrigerant in the heat exchanger to achieve the required degree of superheat while minimizing energy loss. By carefully controlling this temperature difference parameter, the system balances the competing requirements of achieving sufficient superheat for heating capacity while maintaining efficient compressor operation through intermediate-pressure gas injection.
Solution Approach 2:
The system uses feedback control to adjust the operation of the liquid-gas heat exchanger and intermediate-pressure gas injection based on actual operating conditions. This ensures that the degree of superheat and the amount of gas injection are optimized in real-time to maintain both high heating capacity and high coefficient of performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures a sufficient amount of gas refrigerant is injected into the compressor, adequately increasing the COP and space heating capacity, enabling energy efficient heating operations that meet required space heating demands.
Implementation Method 1
the liquid-gas heat exchanger exchanges heat between low-pressure gas refrigerant obtained by evaporating refrigerant in the heat-source-side heat exchanger and high-pressure liquid refrigerant obtained by condensing refrigerant in the utilization-side heat exchanger
Implementation Method 2
high-pressure liquid refrigerant obtained by condensing refrigerant in the utilization-side heat exchanger
Implementation Method 3
low-pressure gas refrigerant obtained by evaporating refrigerant in the heat-source-side heat exchanger
Data Source
AI summary
An air conditioning system includes a refrigerant circuit including a compressor, an indoor heat exchanger, a first expansion valve, a gas-liquid separator, a second expansion valve, and an outdoor heat exchanger which are sequentially connected together to perform a two-stage expansion refrigeration cycle. The refrigerant circuit further includes: a gas injection pipe through which intermediate-pressure gas refrigerant in the gas-liquid separator flows into an intermediate port of the compressor, and a liquid-gas heat exchanger configured to exchange heat between low-pressure gas refrigerant obtained by evaporating refrigerant in the outdoor heat exchanger and travelling toward the compressor and intermediate-pressure liquid refrigerant travelling from the gas-liquid separator toward the second expansion valve.